Sainsbury’s launched its mobile grocery website this week as competition for smartphone spend hots up.

The retailer is offering mobile grocery transactions for the first time. It introduced a transactional general merchandise mobile site last year.

Sainsbury’s mobile food site features more than 20,000 products and the same offers and promotions as the main site.

Sainsbury’s digital and cross channel director Tanya Lawler said: “Customers can browse a full range of grocery products and shop at their convenience – or just add a pint of milk to their shop while waiting for the bus.”

Tesco and Asda are also making plays for mobile spend – each has transactional grocery apps – as the channel takes an increasingly important share of purchases.

Sainsbury’s decided to focus on a mobile website rather than smartphone apps so that it work on all mobiles and operating systems.

The grocer already has non-transactional iPhone, Android and Nokia apps which offer personalised promotions, Nectar points and GPS technology to locate nearby stores.

Sainsbury’s digital and cross channel director Tanya Lawler said: “Customers can now browse a full range of grocery products and shop at their convenience – or just add that pint of milk to their shop while waiting for the bus home.

“We’re confident that the mobile grocery shopping will be a big hit with shoppers.”

Sainsbury’s last week revealed its annual online shopping turnover has reached £800m and grocery orders exceed 165,000 a week.

It now claims to be the second largest online grocer behind Tesco and ahead of Asda, and plans to relaunch its grocery website at the end of this financial year.

Earlier this year Tesco relaunched its non-food Tesco Direct site which was fully configured for mobile devices.

Asda launched an Android app for mobile shopping last month to complement its iPhone app which was released last year.

The Android app allows customers to use voice search to find products or shoppers can scan a barcode to add something to a basket.

Asda chief financial officer Rob McWilliam said last week: “We are making great headway in mobile. We are now processing 15,000 grocery home shopping orders a week.” More than half of Asda’s customers have a smartphone.